Environmental risk limits (ERLs) are derived for di-n-butyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP). The ERLs are derived using data on (eco)toxicology and environmental chemistry. Endpoints used are survival, growth, and reproduction. The resulting ERLs in water are 10 and 0.19 microg/L for DBP and DEHP, respectively; in fresh soil and sediment with 10% organic matter the derived ERLs are respectively 0.7 and 1 mg/kg fresh wt. In The Netherlands, measured concentrations of DBP are seldom above the ERLs, while reported concentrations for DEHP are 3 to 20 times higher than the ERL. As phthalates as a group are commonly mentioned as chemicals with possible endocrine disruptive effects, in vivo and in vitro tests for a series of phthalates with endpoints related to endocrine disruption are reviewed. In vitro and in vivo tests give a similar distinction between phthalates that can or cannot act as endocrine disrupters. The significance of these tests for the derivation of ERLs is discussed. It is concluded that the ERLs derived will give sufficient protection against endocrine disruptive effects. There is no need to include additional data for DBP and DEHP, related to endpoints other than survival, growth, or reproduction, in the derivation of ERLs.